use pekko: in urls and fix other branding issues (#184)

* use pekko: in urls and fix other branding issues

* update comments

* fix artery test

* test changes

* scalafmt

* try to fix some tests and fixing more akka refs

* more akka refs

* more changes

* more akka refs

* Update LeaseMajoritySpec.scala

* Update docs/src/main/paradox/testing.md

Co-authored-by: Johannes Rudolph <johannes.rudolph@gmail.com>

* Update docs/src/main/paradox/project/migration-guides.md

Co-authored-by: Johannes Rudolph <johannes.rudolph@gmail.com>

* Update actor/src/main/scala/org/apache/pekko/serialization/Serialization.scala

Co-authored-by: Johannes Rudolph <johannes.rudolph@gmail.com>

* Update scripts/release-train-issue-template.md

Co-authored-by: Johannes Rudolph <johannes.rudolph@gmail.com>

* revert link-validation change

* Update JacksonModule.scala

* revert key name changes to fix 2 tests

* fix one test

* more test trouble

* more test issues

* fix hashing test

* Update RouterTest.java

* update code comment

---------

Co-authored-by: Johannes Rudolph <johannes.rudolph@gmail.com>

stream-typed/src/test/scala/docs/scaladsl/ActorFlowSpec.scala

@@ -206,7 +206,7 @@ class ActorFlowSpec extends ScalaTestWithActorTestKit with AnyWordSpecLike {
       intercept[RuntimeException] {
         replier ! Asking("TERMINATE", system.deadLetters)
         Await.result(done, 3.seconds)
-      }.getMessage should startWith("Actor watched by [ask()] has terminated! Was: Actor[akka://ActorFlowSpec")
+      }.getMessage should startWith("Actor watched by [ask()] has terminated! Was: Actor[pekko://ActorFlowSpec")
     }
 
   }